A Commitment
by baillierj
Summary: Mycroft has news to share, which prompts John and Sherlock to consider the turns their shared life has taken during the past few years. Post-S4, parent!lock, platonic (at least mostly).


"Do we have to decide on this _now_?" Sherlock groans, snatching his bow off the coffee table so that Rosie can't reach it.

She is one year seven months today - faster than lightning, too clever for her own good, but she doesn't talk. Not yet. Except for one almost recognisable word, _'Da_ ' which clearly belongs to John.

"You want to risk her picking it instead? Could be something embarrassing."

"But how would she even learn what we chose?" Sherlock asks incredulously.

"I'd have to use the word all the time to denominate you when she's around."

"As if _that's_ not awkward at all," Sherlock scoffs. "I've never understood why children are not taught to use people's proper names. Mummy and Daddy are understandable, of course, but the rest could just go by what they were christened with."

"She's not going to be able to say ' _Sherlock_ ' anytime soon. She'll barely be able to put two letters together for a while."

"Well, she isn't saying a whole lot of other things, either," Sherlock shoots back and an angry frown line appears on John's forehead.

It's become a sore spot for John that Rosie has reached all other expected development milestones, but language is taking its time.

"You know what they say - that a child with very advanced motor skills sometimes takes time to catch up with verbal ones."

"I wouldn't talk until the age of three and I turned out fine."

"You could have, though, you just chose not to? At least that's what Mycroft says. It's like you're still making up for it by never shutting up."

Rosie giggles, having found one of her stuffed animal under John's usual armchair. It has become John chair once again, because after three months of rudderless hemming and hawing he had sold the house he'd shared with Mary, packed his bags and Rosie's belongings, and moved back to Baker Street. He hadn't asked for permission, and Sherlock hadn't raised the subject. It was as if it was always meant to happen, and certain events had simply been an unavoidable detour. Neither of them uses such words to describe the devastation left behind by Mary's passing, of course, that would be belittling.

"Eeeeee!" Rosie screeches, and tugs at Sherlock's trouser leg. He picks her up, lifts her so that they're face to face and scrutinises her carefully. She smiles shyly, then reaches out a hand to twirl a finger around one of the curls framing Sherlock's face. "She's been screaming that vowel a lot lately. Sounds like a fire alarm."

"When she starts talking, she's going to eventually be talking about her home life to other kids. What is she going to say, then?"

"That she lives with Daddy and Daddy's friend?"

"And saying that we're flatmates worked _so_ well before," John sighs.

Before Sherlock's un-death, before Mary, and before Rosie, people had tended to assume they were a couple. Now, when they keep showing up in places with a toddler in tow, the level of assumption is even _worse_.

Sherlock attends all pertinent Rosie-related events. Doctor's appointments, parents' nights at the nursery. John hasn't asked why. They don't talk about things that could rip open old wounds. John had once told Sherlock, in a letter, that he'd rather have anyone else than him as help. He might just have to spend the rest of his life trying to negate that angry sentiment with his actions.

He feels overwhelmed most of the time - he's not going to say no to a bit of help and support.

John's phone rings. He curses, assuming it's the surgery calling him in because the evening call locum has phoned in sick. The same had happened last week.

The call turns out not to be the agency after all - it's Mycroft. John does what he always does, goes through what Sherlock has taught him to think of as a pointless ritual of greetings and inquiries after the health of those participating.

Mycroft calls Rosie 'the infant' and John has wondered if that is going to change to 'the teenager' eventually. Sometimes, he calls her by her full name. It's never 'Rosie'. It's like the man wants to keep his distance, not wanting to accept responsibility for having someone like that in his life, someone who's tiny and defenceless and incomprehensible.

Sherlock has surprised everyone by acting the polar opposite. He behaves as though there has always been a nineteen month-old girl in his life. He doesn't complain about the noise, the toys, or the mess, or the novel requirement for routine. He adapts. He _helps out_ , which has prompted John to consider out loud the possibility of aliens having swapped him for an upgraded model.

It is a different Sherlock to the one he had moved in with years ago.

"Would you and Sherlock and your daughter be available for a casual dinner on Saturday?" Mycroft asks.

"I don't have anything on, and there's no case at the moment - Sherlock's just wrapped up a museum forgery one. He's not bored yet, but getting there."

Rosie and Sherlock are sitting on the sofa side by side, Rosie shoving the end of the sash of Sherlock's dressing gown into the crack between the cushions. Sherlock is cradling John's laptop on his knees, an idle hand resting on top of Rosie's thin blonde hair to keep track of her.

"Excellent. We shall be expecting you at six. No need to bring anything," Mycroft says a little bit more sternly than is necessary, "Apart from making sure Sherlock attends."

John has only been to Mycroft's house three times, all of them dictated by necessity rather than a need to socialise. It's big enough to get lost in. Rosie will probably get a kick out of seeing it. Maybe she'll make faces at the creepy ancestral paintings like Sherlock does.

"Casual, huh," John mutters when Mycroft's housekeeper leads them into the dining room.

Sherlock, carrying Rosie, makes his way to the beautifully arranged table and leans slightly forward so that Rosie can see the large flower arrangement in the middle of the table. He tells her the names of the flowers - the latin ones, too, _obviously, how will she learn if you don't teach her these things_ , _honestly, John._

There are candles burning in sticks, the lights have been dimmed slightly and shining cutlery frames large white plates.

John has been looking forward to this - not because he particularly wants to spend his Saturday night in Mycroft's company, but because it'll be nice not having to worry about food tonight, or about entertaining Rosie - going to a new place will be plenty enough. She'll likely go out like a light tonight.

John feels slightly underdressed, as he always does when he goes somewhere with Sherlock. His old, badly ironed shirt and his better pair of jeans are no match for the impeccable, navy blue linen suit Sherlock has donned. John wonders how many expensive suits Sherlock actually owns, since he doesn't seem to care at all when Rosie smears food on them.

Four places have been set, and it clicks in John's head that Mycroft had used the word ' _we_ ' during the phone call. It can't be their parents - they always seem to travel together, and that would warrant five places.

John walks around the table - and notices one more spot reserved by the table, with a high chair and a plastic mug and plate. He wouldn't have expected this from Mycroft - wouldn't have expected him to realise… But then again, he had said ' _daughter_ '. Even if Mycroft had sent a minion to Ikea to buy these things instead of seeing to it himself, John is still rather pleasantly surprised.

Or maybe Sherlock had told Mycroft to do this.

Who is the person joining them for dinner? What are the remaining options?

Suddenly, it feels as though an icicle is sliding down John's back. It couldn't possibly be- Mycroft wouldn't be so utterly idiotic-

John looks up to see Sherlock examining his expression. He has set Rosie down, and she is in the process of crawling under the table. "It's not _her_ ," Sherlock says. "She is never setting foot outside Sherrinford again. You know this." His tone is stern.

"Do I?" John asks. Despite all of Mycroft's and Sherlock's reassurances, how could they promise him that someone assumed to be both their superior in intelligence, could not come up with another genius scheme to escape?

John doesn't like Sherlock visiting her, and he has never offered to come along. Some things are unforgivable. If she were John's sister, well, family is different, so he does understand why Sherlock still feels the need to try to connect. On the other hand, John is not on speaking terms with Harry nowadays, and Eurus has done _so_ much worse.

Maybe he should contact Harry. She has a right to meet her niece, doesn't she? Does she? John arguing that Harry should stay away because a recently relapsed addict would not a good influence for a child, would be the most hypocritical thing ever.

"You know who it is, then?" John asks. They had made an agreement when John had moved back with Rosie in tow: no more secrets. No more hiding things, pretending that it's because they're protecting each other. _Look where it got us_.

"I'm afraid I don't," Sherlock says, and there's a glint curiosity in his eye before he sits down on his haunches to fish young lady Watson from under the table.

"Apologies for making you wait," Mycroft says as he walks in the door, dressed as impeccably as Sherlock in a black suit. He looks content, but a little expectant. "I have let the kitchen know you've arrived. They have assured me dinner will be ready soon."

"We have arrived, yes, but what about the third guest?" Sherlock asks, not beating around the bush. He never does.

Mycroft glances towards the back of the house. "She's already present."

John arranges Rosie into the highchair, not taking a seat himself yet. Rosie is looking at Mycroft like she always does, as though she doesn't quite know how to react to him.

Sherlock grabs a seat opposite John without being prompted.

Mycroft backtracks a few steps into the hallway for a minute, then emerges again, but this time he is accompanied by a thin woman who looks about 35. Her long, blond hair is arranged into a simple chignon. She's wearing black heels, black trousers and a perfectly fitting white silk blouse with a simple gold chain.

John glances at Sherlock and sees him practically staring at Mycroft. John takes in the man's expression - Mycroft looks like his usual calm self, but there is a strange glow in his smile, as though he's trying to stifle the desire to beam with pride.

"I'd like you to meet Alexandra von Brandteigen. Alexandra, meet Sherlock, my brother; Dr John Watson, and Rosamund Mary Watson."

At first, hearing her full name was a dagger to the heart. Then, a stab, now, a pinprick, which John is convinced it will remain until the end of his days.

The woman shakes John's hand, passes over Rosie with barely a glance, and then extends her hand to Sherlock who has risen from his seat. He takes his time offering his own, and John can see the cogs turning. She is being deduced, read interpreted, _dissected_.

"I could also have introduced her as the future Mrs Holmes," Mycroft says when Sherlock takes a step back, eyes still glued to the visage of the woman standing beside his brother.

Sherlock snorts. "Arranging marriages is a little medieval even for you, _brother,_ " he comments, backtracking to his selected chair and crossing his arms. "I guess we can call this travesty off and head home."

Mycroft's smile has waned into one plastered on for the sake of decency. "The future Mrs _Mycroft_ Holmes, that is."

" _Excuse me_?" Sherlock demands. "Mycroft, what _is this_?"

"If your reaction is related to the fact that I have not shared this development with you earlier, it is simply because we made the decision to explore this possibility without outside interference. Mummy was very supportive in this decision."

 _Calm down_ , John mouths to Sherlock across the table but of course, it's pointless.

Sherlock turns to the woman, who is following the proceedings admirably calmly. "Would you excuse us for a moment?" he asks, voice dripping with honey-smeared sarcasm.

"No, she would not," Mycroft says. "If you're determined to cause a scene, please get it over with so that we can eat."

"You don't realise how dangerous it is to bring more people into this? Does she even know about-" Sherlock pauses and gives Mycroft a pointed look.

For once, Mycroft looks slightly surprised at the turn things have taken. "Yes, Alexandra is perfectly aware of Eurus. And, if bringing people into this refers to our lives in general, then I could have given you this very same reminder when it came to joining forces with Dr Watson. Apologies, John."

John shakes his head with an expression signalling that there's no need for such a gesture.

"She is contained. Moreover, she is no reason for the rest of us to stop getting on with our lives. You have done so, and so will I."

Rosie lets out an alarmed jumble of vowels followed by "Da". John gives her a kiss on the top of her head. "It's alright, love, it's just adults talking."

Mycroft gestures to the table. Instead of the one next to Sherlock, Alexandra unsurprisingly selects the unoccupied seat beside John, who pulls out the chair and offers it to her.

Sherlock drops down into his seat and so does Mycroft, taking his time to arrange the cloth napkin into his lap.

Sherlock squeezes his own into a ball and tosses it in front of Rosie.

"So, Alexandra, what do you do, then?" John asks because he can't come up with anything more sensible. He hates it when new people start with asking him about work, because, depending on their own professions, John admitting to being a doctor often shuts them up or makes them start talking about their bunions.

"I'm a judiciary acquisitions auditor for the European Parliament."

"Lawyer," Sherlock translates, sounding like there's a bad taste in his mouth.

"Alexandra is head of the department handling Brexit," Mycroft explains.

"How will it work, then, this marriage of convenience, if you're over there?" Sherlock asks.

Mycroft's maid appears, ladling some sort of greenish soup onto their plates. Sherlock ignores his portion.

Rosie gets a small cupful of what looks like mashed vegetables. She looks impressed with the offerings, so John starts feeding her spoonfuls of it after checking that it's not too hot.

"Alexandra is retaining her job and her apartment in Brussels," Mycroft says.

"Oh, well, there's always Skype," Sherlock snarks.

"Considering you are no stranger to unconventional relationships, I find your disapproval rather unfair. Not to mention impolite," Mycroft chides.

"You're getting married. Why should I care?"

"I was hoping you would, since all three of you are invited to what we are planning as a tasteful, intimate wedding with a limited guest list."

"I'd never hear the end of it from the parental unit if I didn't show, so I hardly have a choice, do I?"

"You always have a choice, but I hope you'll do the right one regarding my request: I would ask you to be the best man."

Sherlock goes pale.

An hour later, once dessert plates have been scraped clean of cheesecake, they decide to walk home since it's relatively warm. Rosie falls asleep practically the minute John gets her coat on and puts her in the stroller that had been parked beside the front steps of the building.

They say goodbye to Mycroft and Alexandra, who are standing in the doorway.

The minute the door clicks shut, John loses it. He bursts out laughing, tears appearing at the edges of his eyes as he tries to contain himself.

Sherlock disapproves. "What the _hell_ , John?"

John, still chucking, leans down to glance at Rosie, who seems oblivious to the world despite the howling laughter he'd just let out. He shakes his head and seems to find something even more worthy of amusement, when he takes in Sherlock's dismayed expression. "Tell me she's not the most boring person in the entire universe. _Hobbies: reading books. 'Sometimes we watch films'_ ", he quotes Alexandra's joyless answer to his own enquiry. "They must've grown her in a lab somewhere to be a politician's wife. And your face, honestly-" John chuckles, and starts steering the stroller.

Sherlock clasps his hands behind his back as they head towards Sloane Street. Belgravia is quiet this time of night - or is it always? Mostly an exclusive residential area, the occupants of South Eaton Place and its surrounding streets don't seem to hang out much outside their CCTV-watched, guarded, meticulously gardened houses. "If one overlooks that blank slate personality, I must admit she must be a very convenient match. Not to mention that she's royalty, which must've whetted Mycroft's appetite. He has always wanted a title. Not that he'll get one, but he certainly won't mind becoming a _Habsburg_ by extension."

"What?!"

Sherlock shrugs. "The Von Brandteigens are a prominent Austrian-British family with direct lineage to the Lorraine branch of the Habsburgs. Shame there isn't a country castle included in the dowry."

"Do you think he loves her?" John voices the question that must be on both their minds. "Or is it a political PR move?"

"I wouldn't put such a thing past Mycroft, no, but his ambitions have never been directed towards becoming prominent in the public eye. He certainly likes a bit of power, but not the sort you get from elections through the fickle will of the Great British Public. He wants _real_ power, and that all happens behind the scenes. No, I rather think he _wants_ a wife because all of his Eton chums must have acquired one at this point."

John had already voiced his amazement over the best man thing an hour earlier: "If you want things done tastefully and without drama, why are you asking _him_?" he had inquired Mycroft with a rather deadpan expression.

"You made that same request to Sherlock once," Mycroft had said, and that had shut John up.

Alexandra had then made a point of asking about Sherlock's work. It had been perhaps the evening's only moment that had not been laden with heavy tension, since Sherlock had never been able to resist an opportunity to show off. However, to John's astonishment, he hadn't fired off any unpleasant deductions about her.

"What about her motivations?" John now asks enthusiastically, expecting to finally hear all that Sherlock must've gleaned from her stockings, the colour of her hair, that gold chain, things she'd said - everything and anything Sherlock can read things from, where other people only see the surface level.

"Like you said, awfully dull. That level of boring takes some work. He must've done a background check - there's nothing there that raised my suspicions. She's a high-achieving paper-pusher, that's all."

"Are you going to do it, then, being best man?" John asks, but receives no answer.

Mycroft had stated one condition on the whole thing: "And for the love of God, Sherlock, _no_ speech. Instead, I was hoping you might play something?"

Alexandra had patted her lips with her napkin and asked, "But why not? I heard the speech you made at Dr Watson's wedding was rather lovely."

John had chuckled. "Who told you that?"

"Greg may have said something on the subject."

Sherlock had turned to Mycroft wearing a venomous glare. "You told Lestrade about her before me?"

"He's an old friend, and we ran into him recently. That is all." Mycroft had then turned to address Alexandra. "The reason I'm allowing him to forgo the agony of writing another best man's speech is that usually it is the groom who makes grand vows, not the best man, and I wish to avoid him insulting at least half the guests."

"Why are you even asking him, then?" John had begun to feel somewhat insulted on Sherlock's behalf.

Mycroft had swallowed a forkful of chateaubriand before answering. "Mummy insisted."

They stop at a red light. "Will he tell Eurus, do you think?" John asks Sherlock.

"Probably. I'm sure she'll get a video of it. She'll not understand a bit of it, of course, but it'll be a nice gesture mostly for the benefit of our parents."

"Listen, Sherlock-" John feels as awkward as he sounds, but this needs saying, "I'm sorry I did that to you. The whole best man thing. I was… Not in a good place. I wanted us all to get along."

"We did get along."

"I know, but it wasn't fair of me."

The explanation of _why_ lingers in the air, unsaid. They don't talk about it - the reason why Mary wasn't a mistake but she was still _the wrong thing_ , and why John's marriage may have been a worse betrayal than a fake gravestone and a two-year absence.

They've both made mistakes. _Quid pro quo._

"It upsets you, him getting married," John muses out loud, which is rather foolhardy of him. Sherlock has lately been better - they've both been better - at the odd thing of talking about feelings and such, but with Sherlock one never knows what the reaction will be, or when he'll clam up completely.

"That's what people do," Sherlock says, sounding bitter. "They get married, and they leave."

"Somehow, I can't imagine you doing that. Marriage, I mean." _And you've already had the chance to plan a wedding for yourself to be a part of_ , John could have added, but that has connotations that fall under things not talked about.

"It's an outdated, pointless, pseudoreligious concept that has no benefits besides judiciary ones."

"That's the Sherlock we know." _And love_ , John omits. Why does he censor himself like that? It's a proverb. Just a proverb.

 _The two people I love and care about._

"You left the reception early," John points out. "You hated every part of it, didn't you? That's why you got all quiet when Mycroft asked you, you've got bad memories." It's a not a question, it's a deduction. "You think marriage is pointless, but the word _does_ mean something to you: _'married to your work_ ', you told me. As in _committed_ to something."

"Why are we discussing this?" Sherlock asks brusquely.

"I think you're more committed to other people than you like to think. I think a lot has changed in six years."

"Agreed," Sherlock says and nods towards the stroller. "And it's not all bad."

"You've been bloody amazing. You really have. You don't have to keep doing things because of what I wrote, you know." John knows that horrible note he's made Molly pass on to Sherlock is still in the flat, carefully folded between Sherlock's copy of his and Mary's wedding invitation and shoved between the pages of an antique copy of Treasure Island in Sherlock's room. John knows it's a bit beneath him to snoop like that, when dropping Sherlock's laundry into his room, but he'd simply thought that Sherlock keeping a childhood book was a bit endearing, so he'd taken it out to have a look.

"Remember what we discussed only this week. At some point, she will start asking after two parents," Sherlock suddenly reminds him, probably as an attempt to change th subject.

"Rosie has two parents. She _had_ a mother, and she has two people who love her and take care of her," John tells him.

"The reason why you married Mary is still relevant - you want a companion."

John grabs Sherlock's sleeve to stop him. He always walks too fast. This is how it has always worked - Sherlock leads, he follows, desperately trying to keep up.

"I have one. I always did. I just couldn't wrap my head around the fact that there are many kinds," John says softly.

Sherlock is looking at him very carefully, _clearly_ unsure of how much to read into John's statement.

"I'm not leaving, Sherlock. I'm not going to uproot Rosie from what is _home_ , what _has_ been my home for six years, even though I stayed away for a bit. What I did before, the casual dating thing, it's a bit not good to expose a kid to that. I don't even want that anymore. I've learned to look at what's in front of me, before it's gone."

If they were _most_ _people_ , this is where they'd join hands. Kiss, perhaps.

They don't.

John doesn't know if Sherlock thinks in those terms - within parameters of love and sex - but right now, he doesn't need to know. Perhaps one day, when a lot more water has flown under the Millennium Bridge, he might ask about those things, and Sherlock might answer, but right now, it doesn't matter. Their focus now needs to be elsewhere, in even bigger things, such as the fledgeling human being fate has given them to raise together. John has never doubted, not for one second, that Sherlock wouldn't be up for such a job. What he lacks in certain social skills and a general sort of faith in humanity, he makes up for in loyalty, creativity, an unexpected patience and a mindset that can somehow relate to how frustrating it is to not understand the world of the adult humans around you.

"I really would like Rosie to call you something else than Sherlock. Not uncle, that would be stupid, but something."

 _Dad? Father?_ John realises he wouldn't mind even those. It feels like he's spent a lifetime explaining himself and Sherlock to others. People will assume things, regardless of how many times he insists it's _not like that_. It's much more important that Rosie has a reference she can understand, than for John to stubbornly hold onto outdated notions of their friendship. It's more. They're more. They always have been, and maybe there isn't a proper word for it.

"I think we should let her decide. Maybe she already has?" Sherlock suggests. "That "Ee" she keeps screaming at me could be it already."

Sherlock reaches out his arm, and John veers the stroller to the right so that he can take over. It might be that Sherlock wants something to do to escape this scrutiny, to buy himself a moment to think about what has been said.

"Mycroft is getting married," he finally says. "Imagine that."

"I'm trying to," John says with a grin.

"Well, it is _his_ sort of a party. He can invite the prime minister, and since he's the groom, he'll get to enjoy an endless supply of cake."

 _I love you_ , John thinks.

 _ **\- The End -**_


End file.
